Provided by: zfsutils-linux_0.6.5.6-0ubuntu30_amd64 
NAME
zfs - configures ZFS file systems
SYNOPSIS
zfs [-?]
zfs create [-p] [-o property=value] ... filesystem
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
zfs destroy [-fnpRrv] filesystem|volume
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
zfs destroy filesystem|volume#bookmark
zfs snapshot | snap [-r] [-o property=value] ...
filesystem@snapname|volume@snapname ...
zfs rollback [-rRf] snapshot
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
zfs promote clone-filesystem
zfs rename [-f] filesystem|volume|snapshot
filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
zfs rename -r snapshot snapshot
zfs list [-r|-d depth][-Hp][-o property[,property]...] [-t type[,type]..]
[-s property] ... [-S property] ... [filesystem|volume|snapshot] ...
zfs set property=value filesystem|volume|snapshot ...
zfs get [-r|-d depth][-Hp][-o field[,...]] [-t type[,...]]
[-s source[,...]] "all" | property[,...] filesystem|volume|snapshot ...
zfs inherit [-rS] property filesystem|volume|snapshot ...
zfs upgrade [-v]
zfs upgrade [-r] [-V version] -a | filesystem
zfs userspace [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs mount
zfs mount [-vO] [-o options] -a | filesystem
zfs unmount | umount [-f] -a | filesystem|mountpoint
zfs share -a | filesystem
zfs unshare -a filesystem|mountpoint
zfs bookmark snapshot bookmark
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
zfs receive | recv [-vnFu] filesystem|volume|snapshot
zfs receive | recv [-vnFu] [-d|-e] filesystem
zfs allow filesystem|volume
zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...]
filesystem|volume
zfs allow [-ld] -e perm|@setname[,...] filesystem|volume
zfs allow -c perm|@setname[,...] filesystem|volume
zfs allow -s @setname perm|@setname[,...] filesystem|volume
zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[,... ]]
filesystem|volume
zfs unallow [-rld] -e [perm|@setname[,... ]] filesystem|volume
zfs unallow [-r] -c [perm|@setname[ ... ]] filesystem|volume
zfs unallow [-r] -s @setname [perm|@setname[,... ]] filesystem|volume
zfs hold [-r] tag snapshot...
zfs holds [-r] snapshot...
zfs release [-r] tag snapshot...
zfs diff [-FHt] snapshot snapshot|filesystem
DESCRIPTION
The zfs command configures ZFS datasets within a ZFS storage pool, as described in
zpool(8). A dataset is identified by a unique path within the ZFS namespace. For example:
pool/{filesystem,volume,snapshot}
where the maximum length of a dataset name is MAXNAMELEN (256 bytes).
A dataset can be one of the following:
file system
A ZFS dataset of type filesystem can be mounted within the standard system namespace
and behaves like other file systems. While ZFS file systems are designed to be POSIX
compliant, known issues exist that prevent compliance in some cases. Applications that
depend on standards conformance might fail due to nonstandard behavior when checking
file system free space.
volume
A logical volume exported as a raw or block device. This type of dataset should only
be used under special circumstances. File systems are typically used in most
environments.
snapshot
A read-only version of a file system or volume at a given point in time. It is
specified as filesystem@name or volume@name.
bookmark
Much like a snapshot, but without the hold on on-disk data. It can be used as the
source of a send (but not for a receive). It is specified as filesystem#name or
volume#name.
ZFS File System Hierarchy
A ZFS storage pool is a logical collection of devices that provide space for datasets. A
storage pool is also the root of the ZFS file system hierarchy.
The root of the pool can be accessed as a file system, such as mounting and unmounting,
taking snapshots, and setting properties. The physical storage characteristics, however,
are managed by the zpool(8) command.
See zpool(8) for more information on creating and administering pools.
Snapshots
A snapshot is a read-only copy of a file system or volume. Snapshots can be created
extremely quickly, and initially consume no additional space within the pool. As data
within the active dataset changes, the snapshot consumes more data than would otherwise be
shared with the active dataset.
Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back.
Visibility is determined by the snapdev property of the parent volume.
File system snapshots can be accessed under the .zfs/snapshot directory in the root of the
file system. Snapshots are automatically mounted on demand and may be unmounted at regular
intervals. The visibility of the .zfs directory can be controlled by the snapdir property.
Bookmarks
A bookmark is like a snapshot, a read-only copy of a file system or volume. Bookmarks can
be created extremely quickly, compared to snapshots, and they consume no additional space
within the pool. Bookmarks can also have arbitrary names, much like snapshots.
Unlike snapshots, bookmarks can not be accessed through the filesystem in any way. From a
storage standpoint a bookmark just provides a way to reference when a snapshot was created
as a distinct object. Bookmarks are initially tied to a snapshot, not the
filesystem/volume, and they will survive if the snapshot itself is destroyed. Since they
are very light weight there's little incentive to destroy them.
Clones
A clone is a writable volume or file system whose initial contents are the same as another
dataset. As with snapshots, creating a clone is nearly instantaneous, and initially
consumes no additional space.
Clones can only be created from a snapshot. When a snapshot is cloned, it creates an
implicit dependency between the parent and child. Even though the clone is created
somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long
as a clone exists. The origin property exposes this dependency, and the destroy command
lists any such dependencies, if they exist.
The clone parent-child dependency relationship can be reversed by using the promote
subcommand. This causes the "origin" file system to become a clone of the specified file
system, which makes it possible to destroy the file system that the clone was created
from.
Mount Points
Creating a ZFS file system is a simple operation, so the number of file systems per system
is likely to be numerous. To cope with this, ZFS automatically manages mounting and
unmounting file systems without the need to edit the /etc/fstab file. All automatically
managed file systems are mounted by ZFS at boot time.
By default, file systems are mounted under /path, where path is the name of the file
system in the ZFS namespace. Directories are created and destroyed as needed.
A file system can also have a mount point set in the mountpoint property. This directory
is created as needed, and ZFS automatically mounts the file system when the zfs mount -a
command is invoked (without editing /etc/fstab). The mountpoint property can be inherited,
so if pool/home has a mount point of /export/stuff, then pool/home/user automatically
inherits a mount point of /export/stuff/user.
A file system mountpoint property of none prevents the file system from being mounted.
If needed, ZFS file systems can also be managed with traditional tools (mount, umount,
/etc/fstab). If a file system's mount point is set to legacy, ZFS makes no attempt to
manage the file system, and the administrator is responsible for mounting and unmounting
the file system.
Deduplication
Deduplication is the process for removing redundant data at the block-level, reducing the
total amount of data stored. If a file system has the dedup property enabled, duplicate
data blocks are removed synchronously. The result is that only unique data is stored and
common components are shared among files.
WARNING: DO NOT ENABLE DEDUPLICATION UNLESS YOU NEED IT AND KNOW EXACTLY WHAT YOU ARE
DOING!
Deduplicating data is a very resource-intensive operation. It is generally recommended
that you have at least 1.25 GB of RAM per 1 TB of storage when you enable deduplication.
But calculating the exact requirenments is a somewhat complicated affair. Please see the
Oracle Dedup Guide for more information..
Enabling deduplication on an improperly-designed system will result in extreme performance
issues (extremely slow filesystem and snapshot deletions etc.) and can potentially lead to
data loss (i.e. unimportable pool due to memory exhaustion) if your system is not built
for this purpose. Deduplication affects the processing power (CPU), disks (and the
controller) as well as primary (real) memory.
Before creating a pool with deduplication enabled, ensure that you have planned your
hardware requirements appropriately and implemented appropriate recovery practices, such
as regular backups.
Unless necessary, deduplication should NOT be enabled on a system. Instead, consider using
compression=lz4, as a less resource-intensive alternative.
Native Properties
Properties are divided into two types, native properties and user-defined (or "user")
properties. Native properties either export internal statistics or control ZFS behavior.
In addition, native properties are either editable or read-only. User properties have no
effect on ZFS behavior, but you can use them to annotate datasets in a way that is
meaningful in your environment. For more information about user properties, see the "User
Properties" section, below.
Every dataset has a set of properties that export statistics about the dataset as well as
control various behaviors. Properties are inherited from the parent unless overridden by
the child. Some properties apply only to certain types of datasets (file systems, volumes,
or snapshots).
The values of numeric properties can be specified using human-readable suffixes (for
example, k, KB, M, Gb, and so forth, up to Z for zettabyte). The following are all valid
(and equal) specifications:
1536M, 1.5g, 1.50GB
The values of non-numeric properties are case sensitive and must be lowercase, except for
mountpoint, sharenfs, and sharesmb.
The following native properties consist of read-only statistics about the dataset. These
properties can be neither set, nor inherited. Native properties apply to all dataset types
unless otherwise noted.
available
The amount of space available to the dataset and all its children, assuming that there
is no other activity in the pool. Because space is shared within a pool, availability
can be limited by any number of factors, including physical pool size, quotas,
reservations, or other datasets within the pool.
This property can also be referred to by its shortened column name, avail.
compressratio
For non-snapshots, the compression ratio achieved for the used space of this dataset,
expressed as a multiplier. The used property includes descendant datasets, and, for
clones, does not include the space shared with the origin snapshot. For snapshots,
the compressratio is the same as the refcompressratio property. Compression can be
turned on by running: zfs set compression=on dataset. The default value is off.
creation
The time this dataset was created.
clones
For snapshots, this property is a comma-separated list of filesystems or volumes which
are clones of this snapshot. The clones' origin property is this snapshot. If the
clones property is not empty, then this snapshot can not be destroyed (even with the
-r or -f options).
defer_destroy
This property is on if the snapshot has been marked for deferred destruction by using
the zfs destroy -d command. Otherwise, the property is off.
filesystem_count
The total number of filesystems and volumes that exist under this location in the
dataset tree. This value is only available when a filesystem_limit has been set
somewhere in the tree under which the dataset resides.
logicalreferenced
The amount of space that is "logically" accessible by this dataset. See the
referenced property. The logical space ignores the effect of the compression and
copies properties, giving a quantity closer to the amount of data that applications
see. However, it does include space consumed by metadata.
This property can also be referred to by its shortened column name, lrefer.
logicalused
The amount of space that is "logically" consumed by this dataset and all its
descendents. See the used property. The logical space ignores the effect of the
compression and copies properties, giving a quantity closer to the amount of data that
applications see. However, it does include space consumed by metadata.
This property can also be referred to by its shortened column name, lused.
mounted
For file systems, indicates whether the file system is currently mounted. This
property can be either yes or no.
origin
For cloned file systems or volumes, the snapshot from which the clone was created. See
also the clones property.
referenced
The amount of data that is accessible by this dataset, which may or may not be shared
with other datasets in the pool. When a snapshot or clone is created, it initially
references the same amount of space as the file system or snapshot it was created
from, since its contents are identical.
This property can also be referred to by its shortened column name, refer.
refcompressratio
The compression ratio achieved for the referenced space of this dataset, expressed as
a multiplier. See also the compressratio property.
snapshot_count
The total number of snapshots that exist under this location in the dataset tree.
This value is only available when a snapshot_limit has been set somewhere in the tree
under which the dataset resides.
type
The type of dataset: filesystem, volume, or snapshot.
used
The amount of space consumed by this dataset and all its descendents. This is the
value that is checked against this dataset's quota and reservation. The space used
does not include this dataset's reservation, but does take into account the
reservations of any descendent datasets. The amount of space that a dataset consumes
from its parent, as well as the amount of space that are freed if this dataset is
recursively destroyed, is the greater of its space used and its reservation.
When snapshots (see the "Snapshots" section) are created, their space is initially
shared between the snapshot and the file system, and possibly with previous snapshots.
As the file system changes, space that was previously shared becomes unique to the
snapshot, and counted in the snapshot's space used. Additionally, deleting snapshots
can increase the amount of space unique to (and used by) other snapshots.
The amount of space used, available, or referenced does not take into account pending
changes. Pending changes are generally accounted for within a few seconds. Committing
a change to a disk using fsync(2) or O_SYNC does not necessarily guarantee that the
space usage information is updated immediately.
usedby*
The usedby* properties decompose the used properties into the various reasons that
space is used. Specifically, used = usedbychildren + usedbydataset +
usedbyrefreservation +, usedbysnapshots. These properties are only available for
datasets created on zpool "version 13" pools.
usedbychildren
The amount of space used by children of this dataset, which would be freed if all the
dataset's children were destroyed.
usedbydataset
The amount of space used by this dataset itself, which would be freed if the dataset
were destroyed (after first removing any refreservation and destroying any necessary
snapshots or descendents).
usedbyrefreservation
The amount of space used by a refreservation set on this dataset, which would be freed
if the refreservation was removed.
usedbysnapshots
The amount of space consumed by snapshots of this dataset. In particular, it is the
amount of space that would be freed if all of this dataset's snapshots were destroyed.
Note that this is not simply the sum of the snapshots' used properties because space
can be shared by multiple snapshots.
userused@user
The amount of space consumed by the specified user in this dataset. Space is charged
to the owner of each file, as displayed by ls -l. The amount of space charged is
displayed by du and ls -s. See the zfs userspace subcommand for more information.
Unprivileged users can access only their own space usage. The root user, or a user who
has been granted the userused privilege with zfs allow, can access everyone's usage.
The userused@... properties are not displayed by zfs get all. The user's name must be
appended after the @ symbol, using one of the following forms:
o POSIX name (for example, joe)
o POSIX numeric ID (for example, 789)
o SID name (for example, joe.smith@mydomain)
o SID numeric ID (for example, S-1-123-456-789)
userrefs
This property is set to the number of user holds on this snapshot. User holds are set
by using the zfs hold command.
groupused@group
The amount of space consumed by the specified group in this dataset. Space is charged
to the group of each file, as displayed by ls -l. See the userused@user property for
more information.
Unprivileged users can only access their own groups' space usage. The root user, or a
user who has been granted the groupused privilege with zfs allow, can access all
groups' usage.
volblocksize=blocksize
For volumes, specifies the block size of the volume. The blocksize cannot be changed
once the volume has been written, so it should be set at volume creation time. The
default blocksize for volumes is 8 Kbytes. Any power of 2 from 512 bytes to 128 Kbytes
is valid.
This property can also be referred to by its shortened column name, volblock.
written
The amount of referenced space written to this dataset since the previous snapshot.
written@snapshot
The amount of referenced space written to this dataset since the specified snapshot.
This is the space that is referenced by this dataset but was not referenced by the
specified snapshot.
The snapshot may be specified as a short snapshot name (just the part after the @), in
which case it will be interpreted as a snapshot in the same filesystem as this
dataset. The snapshot be a full snapshot name (filesystem@snapshot), which for clones
may be a snapshot in the origin's filesystem (or the origin of the origin's
filesystem, etc).
The following native properties can be used to change the behavior of a ZFS dataset.
aclinherit=discard | noallow | restricted | passthrough | passthrough-x
Controls how ACL entries are inherited when files and directories are created. A file
system with an aclinherit property of discard does not inherit any ACL entries. A file
system with an aclinherit property value of noallow only inherits inheritable ACL
entries that specify "deny" permissions. The property value restricted (the default)
removes the write_acl and write_owner permissions when the ACL entry is inherited. A
file system with an aclinherit property value of passthrough inherits all inheritable
ACL entries without any modifications made to the ACL entries when they are inherited.
A file system with an aclinherit property value of passthrough-x has the same meaning
as passthrough, except that the owner@, group@, and everyone@ ACEs inherit the execute
permission only if the file creation mode also requests the execute bit.
When the property value is set to passthrough, files are created with a mode
determined by the inheritable ACEs. If no inheritable ACEs exist that affect the mode,
then the mode is set in accordance to the requested mode from the application.
The aclinherit property does not apply to Posix ACLs.
acltype=noacl | posixacl
Controls whether ACLs are enabled and if so what type of ACL to use. When a file
system has the acltype property set to noacl (the default) then ACLs are disabled.
Setting the acltype property to posixacl indicates Posix ACLs should be used. Posix
ACLs are specific to Linux and are not functional on other platforms. Posix ACLs are
stored as an xattr and therefore will not overwrite any existing ZFS/NFSv4 ACLs which
may be set. Currently only posixacls are supported on Linux.
To obtain the best performance when setting posixacl users are strongly encouraged to
set the xattr=sa property. This will result in the Posix ACL being stored more
efficiently on disk. But as a consequence of this all new xattrs will only be
accessible from ZFS implementations which support the xattr=sa property. See the
xattr property for more details.
atime=on | off
Controls whether the access time for files is updated when they are read. Turning this
property off avoids producing write traffic when reading files and can result in
significant performance gains, though it might confuse mailers and other similar
utilities. The default value is on. See also relatime below.
canmount=on | off | noauto
If this property is set to off, the file system cannot be mounted, and is ignored by
zfs mount -a. Setting this property to off is similar to setting the mountpoint
property to none, except that the dataset still has a normal mountpoint property,
which can be inherited. Setting this property to off allows datasets to be used solely
as a mechanism to inherit properties. One example of setting canmount=off is to have
two datasets with the same mountpoint, so that the children of both datasets appear in
the same directory, but might have different inherited characteristics.
When the noauto option is set, a dataset can only be mounted and unmounted explicitly.
The dataset is not mounted automatically when the dataset is created or imported, nor
is it mounted by the zfs mount -a command or unmounted by the zfs unmount -a command.
This property is not inherited.
checksum=on | off | fletcher2,| fletcher4 | sha256
Controls the checksum used to verify data integrity. The default value is on, which
automatically selects an appropriate algorithm (currently, fletcher4, but this may
change in future releases). The value off disables integrity checking on user data.
Disabling checksums is NOT a recommended practice.
Changing this property affects only newly-written data.
compression=on | off | lzjb | lz4 | gzip | gzip-N | zle
Controls the compression algorithm used for this dataset.
Setting compression to on indicates that the current default compression algorithm
should be used. The default balances compression and decompression speed, with
compression ratio and is expected to work well on a wide variety of workloads. Unlike
all other settings for this property, on does not select a fixed compression type. As
new compression algorithms are added to ZFS and enabled on a pool, the default
compression algorithm may change. The current default compression algorthm is either
lzjb or, if the lz4_compress feature is enabled, lz4.
The lzjb compression algorithm is optimized for performance while providing decent
data compression.
The lz4 compression algorithm is a high-performance replacement for the lzjb
algorithm. It features significantly faster compression and decompression, as well as
a moderately higher compression ratio than lzjb, but can only be used on pools with
the lz4_compress feature set to enabled. See zpool-features(5) for details on ZFS
feature flags and the lz4_compress feature.
The gzip compression algorithm uses the same compression as the gzip(1) command. You
can specify the gzip level by using the value gzip-N where N is an integer from 1
(fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6
(which is also the default for gzip(1)). The zle compression algorithm compresses runs
of zeros.
This property can also be referred to by its shortened column name compress. Changing
this property affects only newly-written data.
copies=1 | 2 | 3
Controls the number of copies of data stored for this dataset. These copies are in
addition to any redundancy provided by the pool, for example, mirroring or RAID-Z. The
copies are stored on different disks, if possible. The space used by multiple copies
is charged to the associated file and dataset, changing the used property and counting
against quotas and reservations.
Changing this property only affects newly-written data. Therefore, set this property
at file system creation time by using the -o copies=N option.
dedup=on | off | verify | sha256[,verify]
Controls whether deduplication is in effect for a dataset. The default value is off.
The default checksum used for deduplication is sha256 (subject to change). When dedup
is enabled, the dedup checksum algorithm overrides the checksum property. Setting the
value to verify is equivalent to specifying sha256,verify.
If the property is set to verify, then, whenever two blocks have the same signature,
ZFS will do a byte-for-byte comparison with the existing block to ensure that the
contents are identical.
Unless necessary, deduplication should NOT be enabled on a system. See Deduplication
above.
devices=on | off
Controls whether device nodes can be opened on this file system. The default value is
on.
exec=on | off
Controls whether processes can be executed from within this file system. The default
value is on.
mlslabel=label | none
The mlslabel property is a sensitivity label that determines if a dataset can be
mounted in a zone on a system with Trusted Extensions enabled. If the labeled dataset
matches the labeled zone, the dataset can be mounted and accessed from the labeled
zone.
When the mlslabel property is not set, the default value is none. Setting the
mlslabel property to none is equivalent to removing the property.
The mlslabel property can be modified only when Trusted Extensions is enabled and only
with appropriate privilege. Rights to modify it cannot be delegated. When changing a
label to a higher label or setting the initial dataset label, the
{PRIV_FILE_UPGRADE_SL} privilege is required. When changing a label to a lower label
or the default (none), the {PRIV_FILE_DOWNGRADE_SL} privilege is required. Changing
the dataset to labels other than the default can be done only when the dataset is not
mounted. When a dataset with the default label is mounted into a labeled-zone, the
mount operation automatically sets the mlslabel property to the label of that zone.
When Trusted Extensions is not enabled, only datasets with the default label (none)
can be mounted.
Zones are a Solaris feature and are not relevant on Linux.
filesystem_limit=count | none
Limits the number of filesystems and volumes that can exist under this point in the
dataset tree. The limit is not enforced if the user is allowed to change the limit.
Setting a filesystem_limit on a descendent of a filesystem that already has a
filesystem_limit does not override the ancestor's filesystem_limit, but rather imposes
an additional limit. This feature must be enabled to be used (see zpool-features(5)).
mountpoint=path | none | legacy
Controls the mount point used for this file system. See the "Mount Points" section for
more information on how this property is used.
When the mountpoint property is changed for a file system, the file system and any
children that inherit the mount point are unmounted. If the new value is legacy, then
they remain unmounted. Otherwise, they are automatically remounted in the new location
if the property was previously legacy or none, or if they were mounted before the
property was changed. In addition, any shared file systems are unshared and shared in
the new location.
nbmand=on | off
Controls whether the file system should be mounted with nbmand (Non Blocking mandatory
locks). This is used for CIFS clients. Changes to this property only take effect when
the file system is umounted and remounted. See mount(8) for more information on nbmand
mounts.
primarycache=all | none | metadata
Controls what is cached in the primary cache (ARC). If this property is set to all,
then both user data and metadata is cached. If this property is set to none, then
neither user data nor metadata is cached. If this property is set to metadata, then
only metadata is cached. The default value is all.
quota=size | none
Limits the amount of space a dataset and its descendents can consume. This property
enforces a hard limit on the amount of space used. This includes all space consumed by
descendents, including file systems and snapshots. Setting a quota on a descendent of
a dataset that already has a quota does not override the ancestor's quota, but rather
imposes an additional limit.
Quotas cannot be set on volumes, as the volsize property acts as an implicit quota.
snapshot_limit=count | none
Limits the number of snapshots that can be created on a dataset and its descendents.
Setting a snapshot_limit on a descendent of a dataset that already has a
snapshot_limit does not override the ancestor's snapshot_limit, but rather imposes an
additional limit. The limit is not enforced if the user is allowed to change the
limit. For example, this means that recursive snapshots taken from the global zone are
counted against each delegated dataset within a zone. This feature must be enabled to
be used (see zpool-features(5)).
userquota@user=size | none
Limits the amount of space consumed by the specified user. Similar to the refquota
property, the userquota space calculation does not include space that is used by
descendent datasets, such as snapshots and clones. User space consumption is
identified by the userspace@user property.
Enforcement of user quotas may be delayed by several seconds. This delay means that a
user might exceed their quota before the system notices that they are over quota and
begins to refuse additional writes with the EDQUOT error message . See the zfs
userspace subcommand for more information.
Unprivileged users can only access their own groups' space usage. The root user, or a
user who has been granted the userquota privilege with zfs allow, can get and set
everyone's quota.
This property is not available on volumes, on file systems before version 4, or on
pools before version 15. The userquota@... properties are not displayed by zfs get
all. The user's name must be appended after the @ symbol, using one of the following
forms:
o POSIX name (for example, joe)
o POSIX numeric ID (for example, 789)
o SID name (for example, joe.smith@mydomain)
o SID numeric ID (for example, S-1-123-456-789)
groupquota@group=size | none
Limits the amount of space consumed by the specified group. Group space consumption is
identified by the userquota@user property.
Unprivileged users can access only their own groups' space usage. The root user, or a
user who has been granted the groupquota privilege with zfs allow, can get and set all
groups' quotas.
readonly=on | off
Controls whether this dataset can be modified. The default value is off.
This property can also be referred to by its shortened column name, rdonly.
recordsize=size
Specifies a suggested block size for files in the file system. This property is
designed solely for use with database workloads that access files in fixed-size
records. ZFS automatically tunes block sizes according to internal algorithms
optimized for typical access patterns.
For databases that create very large files but access them in small random chunks,
these algorithms may be suboptimal. Specifying a recordsize greater than or equal to
the record size of the database can result in significant performance gains. Use of
this property for general purpose file systems is strongly discouraged, and may
adversely affect performance.
The size specified must be a power of two greater than or equal to 512 and less than
or equal to 128 Kbytes.
Changing the file system's recordsize affects only files created afterward; existing
files are unaffected.
This property can also be referred to by its shortened column name, recsize.
redundant_metadata=all | most
Controls what types of metadata are stored redundantly. ZFS stores an extra copy of
metadata, so that if a single block is corrupted, the amount of user data lost is
limited. This extra copy is in addition to any redundancy provided at the pool level
(e.g. by mirroring or RAID-Z), and is in addition to an extra copy specified by the
copies property (up to a total of 3 copies). For example if the pool is mirrored,
copies=2, and redundant_metadata=most, then ZFS stores 6 copies of most metadata, and
4 copies of data and some metadata.
When set to all, ZFS stores an extra copy of all metadata. If a single on-disk block
is corrupt, at worst a single block of user data (which is recordsize bytes long) can
be lost.
When set to most, ZFS stores an extra copy of most types of metadata. This can
improve performance of random writes, because less metadata must be written. In
practice, at worst about 100 blocks (of recordsize bytes each) of user data can be
lost if a single on-disk block is corrupt. The exact behavior of which metadata
blocks are stored redundantly may change in future releases.
The default value is all.
refquota=size | none
Limits the amount of space a dataset can consume. This property enforces a hard limit
on the amount of space used. This hard limit does not include space used by
descendents, including file systems and snapshots.
refreservation=size | none
The minimum amount of space guaranteed to a dataset, not including its descendents.
When the amount of space used is below this value, the dataset is treated as if it
were taking up the amount of space specified by refreservation. The refreservation
reservation is accounted for in the parent datasets' space used, and counts against
the parent datasets' quotas and reservations.
If refreservation is set, a snapshot is only allowed if there is enough free pool
space outside of this reservation to accommodate the current number of "referenced"
bytes in the dataset.
This property can also be referred to by its shortened column name, refreserv.
relatime=on | off
Controls the manner in which the access time is updated when atime=on is set. Turning
this property on causes the access time to be updated relative to the modify or change
time. Access time is only updated if the previous access time was earlier than the
current modify or change time or if the existing access time hasn't been updated
within the past 24 hours. The default value is off.
reservation=size | none
The minimum amount of space guaranteed to a dataset and its descendents. When the
amount of space used is below this value, the dataset is treated as if it were taking
up the amount of space specified by its reservation. Reservations are accounted for in
the parent datasets' space used, and count against the parent datasets' quotas and
reservations.
This property can also be referred to by its shortened column name, reserv.
secondarycache=all | none | metadata
Controls what is cached in the secondary cache (L2ARC). If this property is set to
all, then both user data and metadata is cached. If this property is set to none, then
neither user data nor metadata is cached. If this property is set to metadata, then
only metadata is cached. The default value is all.
setuid=on | off
Controls whether the set-UID bit is respected for the file system. The default value
is on.
shareiscsi=on | off
Like the sharenfs property, shareiscsi indicates whether a ZFS volume is exported as
an iSCSI target. The acceptable values for this property are on, off, and type=disk.
The default value is off. In the future, other target types might be supported. For
example, tape.
You might want to set shareiscsi=on for a file system so that all ZFS volumes within
the file system are shared by default. However, setting this property on a file system
has no direct effect.
sharesmb=on | off
Controls whether the file system is shared by using Samba USERSHARES, and what options
are to be used. Otherwise, the file system is automatically shared and unshared with
the zfs share and zfs unshare commands. If the property is set to on, the net(8)
command is invoked to create a USERSHARE.
Because SMB shares requires a resource name, a unique resource name is constructed
from the dataset name. The constructed name is a copy of the dataset name except that
the characters in the dataset name, which would be illegal in the resource name, are
replaced with underscore (_) characters. The ZFS On Linux driver does not (yet)
support additional options which might be available in the Solaris version.
If the sharesmb property is set to off, the file systems are unshared.
In Linux, the share is created with the ACL (Access Control List) "Everyone:F" ("F"
stands for "full permissions", ie. read and write permissions) and no guest access
(which means samba must be able to authenticate a real user, system passwd/shadow,
ldap or smbpasswd based) by default. This means that any additional access control
(dissalow specific user specific access etc) must be done on the underlaying
filesystem.
Example to mount a SMB filesystem shared through ZFS (share/tmp): Note that a user
and his/her password must be given!
smbmount //127.0.0.1/share_tmp /mnt/tmp -o
user=workgroup/turbo,password=obrut,uid=1000
Minimal /etc/samba/smb.conf configuration
* Samba will need to listen to 'localhost' (127.0.0.1) for the zfs utilities to
communitate with samba. This is the default behavior for most Linux distributions.
* Samba must be able to authenticate a user. This can be done in a number of ways,
depending on if using the system password file, LDAP or the Samba specific smbpasswd
file. How to do this is outside the scope of this manual. Please refer to the
smb.conf(5) manpage for more information.
* See the USERSHARE section of the smb.conf(5) man page for all configuration
options in case you need to modify any options to the share afterwards. Do note that
any changes done with the 'net' command will be undone if the share is every
unshared (such as at a reboot etc). In the future, ZoL will be able to set specific
options directly using sharesmb=<option>.
sharenfs=on | off | opts
Controls whether the file system is shared via NFS, and what options are used. A file
system with a sharenfs property of off is managed with the exportfs(8) command and
entries in /etc/exports file. Otherwise, the file system is automatically shared and
unshared with the zfs share and zfs unshare commands. If the property is set to on,
the dataset is shared using the exportfs(8) command in the following manner (see
exportfs(8) for the meaning of the different options):
/usr/sbin/exportfs -i -o sec=sys,rw,no_subtree_check,no_root_squash,mountpoint *:<mountpoint of dataset>
Otherwise, the exportfs(8) command is invoked with options equivalent to the contents
of this property.
When the sharenfs property is changed for a dataset, the dataset and any children
inheriting the property are re-shared with the new options, only if the property was
previously off, or if they were shared before the property was changed. If the new
property is off, the file systems are unshared.
logbias = latency | throughput
Provide a hint to ZFS about handling of synchronous requests in this dataset. If
logbias is set to latency (the default), ZFS will use pool log devices (if configured)
to handle the requests at low latency. If logbias is set to throughput, ZFS will not
use configured pool log devices. ZFS will instead optimize synchronous operations for
global pool throughput and efficient use of resources.
snapdev=hidden | visible
Controls whether the snapshots devices of zvol's are hidden or visible. The default
value is hidden.
snapdir=hidden | visible
Controls whether the .zfs directory is hidden or visible in the root of the file
system as discussed in the "Snapshots" section. The default value is hidden.
sync=standard | always | disabled
Controls the behavior of synchronous requests (e.g. fsync, O_DSYNC). standard is the
POSIX specified behavior of ensuring all synchronous requests are written to stable
storage and all devices are flushed to ensure data is not cached by device controllers
(this is the default). always causes every file system transaction to be written and
flushed before its system call returns. This has a large performance penalty. disabled
disables synchronous requests. File system transactions are only committed to stable
storage periodically. This option will give the highest performance. However, it is
very dangerous as ZFS would be ignoring the synchronous transaction demands of
applications such as databases or NFS. Administrators should only use this option
when the risks are understood.
version=1 | 2 | current
The on-disk version of this file system, which is independent of the pool version.
This property can only be set to later supported versions. See the zfs upgrade
command.
volsize=size
For volumes, specifies the logical size of the volume. By default, creating a volume
establishes a reservation of equal size. For storage pools with a version number of 9
or higher, a refreservation is set instead. Any changes to volsize are reflected in an
equivalent change to the reservation (or refreservation). The volsize can only be set
to a multiple of volblocksize, and cannot be zero.
The reservation is kept equal to the volume's logical size to prevent unexpected
behavior for consumers. Without the reservation, the volume could run out of space,
resulting in undefined behavior or data corruption, depending on how the volume is
used. These effects can also occur when the volume size is changed while it is in use
(particularly when shrinking the size). Extreme care should be used when adjusting the
volume size.
Though not recommended, a "sparse volume" (also known as "thin provisioning") can be
created by specifying the -s option to the zfs create -V command, or by changing the
reservation after the volume has been created. A "sparse volume" is a volume where the
reservation is less then the volume size. Consequently, writes to a sparse volume can
fail with ENOSPC when the pool is low on space. For a sparse volume, changes to
volsize are not reflected in the reservation.
vscan=on | off
Controls whether regular files should be scanned for viruses when a file is opened and
closed. In addition to enabling this property, the virus scan service must also be
enabled for virus scanning to occur. The default value is off.
xattr=on | off | sa
Controls whether extended attributes are enabled for this file system. Two styles of
extended attributes are supported either directory based or system attribute based.
The default value of on enables directory based extended attributes. This style of
xattr imposes no practical limit on either the size or number of xattrs which may be
set on a file. Although under Linux the getxattr(2) and setxattr(2) system calls
limit the maximum xattr size to 64K. This is the most compatible style of xattr and
it is supported by the majority of ZFS implementations.
System attribute based xattrs may be enabled by setting the value to sa. The key
advantage of this type of xattr is improved performance. Storing xattrs as system
attributes significantly decreases the amount of disk IO required. Up to 64K of xattr
data may be stored per file in the space reserved for system attributes. If there is
not enough space available for an xattr then it will be automatically written as a
directory based xattr. System attribute based xattrs are not accessible on platforms
which do not support the xattr=sa feature.
The use of system attribute based xattrs is strongly encouraged for users of SELinux
or Posix ACLs. Both of these features heavily rely of xattrs and benefit
significantly from the reduced xattr access time.
zoned=on | off
Controls whether the dataset is managed from a non-global zone. Zones are a Solaris
feature and are not relevant on Linux. The default value is off.
The following three properties cannot be changed after the file system is created, and
therefore, should be set when the file system is created. If the properties are not set
with the zfs create or zpool create commands, these properties are inherited from the
parent dataset. If the parent dataset lacks these properties due to having been created
prior to these features being supported, the new file system will have the default values
for these properties.
casesensitivity=sensitive | insensitive | mixed
Indicates whether the file name matching algorithm used by the file system should be
case-sensitive, case-insensitive, or allow a combination of both styles of matching.
The default value for the casesensitivity property is sensitive. Traditionally, UNIX
and POSIX file systems have case-sensitive file names.
The mixed value for the casesensitivity property indicates that the file system can
support requests for both case-sensitive and case-insensitive matching behavior.
Currently, case-insensitive matching behavior on a file system that supports mixed
behavior is limited to the Solaris CIFS server product. For more information about the
mixed value behavior, see the Solaris ZFS Administration Guide.
normalization = none | formC | formD | formKC | formKD
Indicates whether the file system should perform a unicode normalization of file names
whenever two file names are compared, and which normalization algorithm should be
used. File names are always stored unmodified, names are normalized as part of any
comparison process. If this property is set to a legal value other than none, and the
utf8only property was left unspecified, the utf8only property is automatically set to
on. The default value of the normalization property is none. This property cannot be
changed after the file system is created.
utf8only=on | off
Indicates whether the file system should reject file names that include characters
that are not present in the UTF-8 character code set. If this property is explicitly
set to off, the normalization property must either not be explicitly set or be set to
none. The default value for the utf8only property is off. This property cannot be
changed after the file system is created.
The casesensitivity, normalization, and utf8only properties are also new permissions that
can be assigned to non-privileged users by using the ZFS delegated administration feature.
context=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for all files in the filesytem under the mountpoint
for that filesystem. See selinux(8) for more information.
fscontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the filesytem being mounted. See selinux(8)
for more information.
defntext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for unlabeled files. See selinux(8) for more
information.
rootcontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the root inode of the filesystem. See
selinux(8) for more information.
overlay=on | off
Allow mounting on a busy directory or a directory which already contains
files/directories. This is the default mount behavior for Linux filesystems. However,
for consistency with ZFS on other platforms overlay mounts are disabled by default.
Set overlay=on to enable overlay mounts.
Temporary Mount Point Properties
When a file system is mounted, either through mount(8) for legacy mounts or the zfs mount
command for normal file systems, its mount options are set according to its properties.
The correlation between properties and mount options is as follows:
PROPERTY MOUNT OPTION
devices devices/nodevices
exec exec/noexec
readonly ro/rw
setuid setuid/nosetuid
xattr xattr/noxattr
atime atime/noatime
relatime relatime/norelatime
nbmand nbmand/nonbmand
In addition, these options can be set on a per-mount basis using the -o option, without
affecting the property that is stored on disk. The values specified on the command line
override the values stored in the dataset. The -nosuid option is an alias for
nodevices,nosetuid. These properties are reported as "temporary" by the zfs get command.
If the properties are changed while the dataset is mounted, the new setting overrides any
temporary settings.
User Properties
In addition to the standard native properties, ZFS supports arbitrary user properties.
User properties have no effect on ZFS behavior, but applications or administrators can use
them to annotate datasets (file systems, volumes, and snapshots).
User property names must contain a colon (:) character to distinguish them from native
properties. They may contain lowercase letters, numbers, and the following punctuation
characters: colon (:), dash (-), period (.), and underscore (_). The expected convention
is that the property name is divided into two portions such as module:property, but this
namespace is not enforced by ZFS. User property names can be at most 256 characters, and
cannot begin with a dash (-).
When making programmatic use of user properties, it is strongly suggested to use a
reversed DNS domain name for the module component of property names to reduce the chance
that two independently-developed packages use the same property name for different
purposes. For example, property names beginning with com.sun. are reserved for use by
Oracle Corporation (which acquired Sun Microsystems).
The values of user properties are arbitrary strings, are always inherited, and are never
validated. All of the commands that operate on properties (zfs list, zfs get, zfs set, and
so forth) can be used to manipulate both native properties and user properties. Use the
zfs inherit command to clear a user property . If the property is not defined in any
parent dataset, it is removed entirely. Property values are limited to 1024 characters.
ZFS Volumes as Swap
ZFS volumes may be used as Linux swap devices. After creating the volume with the zfs
create command set up and enable the swap area using the mkswap(8) and swapon(8) commands.
Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not
supported.
SUBCOMMANDS
All subcommands that modify state are logged persistently to the pool in their original
form.
zfs ?
Displays a help message.
zfs create [-p] [-o property=value] ... filesystem
Creates a new ZFS file system. The file system is automatically mounted according to
the mountpoint property inherited from the parent.
-p
Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. Any property specified on the command line using the -o option is ignored.
If the target filesystem already exists, the operation completes successfully.
-o property=value
Sets the specified property as if the command zfs set property=value was invoked
at the same time the dataset was created. Any editable ZFS property can also be
set at creation time. Multiple -o options can be specified. An error results if
the same property is specified in multiple -o options.
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
Creates a volume of the given size. The volume is exported as a block device in
/dev/zvol/path, where path is the name of the volume in the ZFS namespace. The size
represents the logical size as exported by the device. By default, a reservation of
equal size is created.
size is automatically rounded up to the nearest 128 Kbytes to ensure that the volume
has an integral number of blocks regardless of blocksize.
-p
Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. Any property specified on the command line using the -o option is ignored.
If the target filesystem already exists, the operation completes successfully.
-s
Creates a sparse volume with no reservation. See volsize in the Native Properties
section for more information about sparse volumes.
-o property=value
Sets the specified property as if the zfs set property=value command was invoked
at the same time the dataset was created. Any editable ZFS property can also be
set at creation time. Multiple -o options can be specified. An error results if
the same property is specified in multiple -o options.
-b blocksize
Equivalent to -o volblocksize=blocksize. If this option is specified in
conjunction with -o volblocksize, the resulting behavior is undefined.
zfs destroy [-fnpRrv] filesystem|volume
Destroys the given dataset. By default, the command unshares any file systems that are
currently shared, unmounts any file systems that are currently mounted, and refuses to
destroy a dataset that has active dependents (children or clones).
-r
Recursively destroy all children.
-R
Recursively destroy all dependents, including cloned file systems outside the
target hierarchy.
-f
Force an unmount of any file systems using the unmount -f command. This option has
no effect on non-file systems or unmounted file systems.
-n
Do a dry-run ("No-op") deletion. No data will be deleted. This is useful in
conjunction with the -v or -p flags to determine what data would be deleted.
-p
Print machine-parsable verbose information about the deleted data.
-v
Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R options, as they
can destroy large portions of a pool and cause unexpected behavior for mounted file
systems in use.
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
The given snapshots are destroyed immediately if and only if the zfs destroy command
without the -d option would have destroyed it. Such immediate destruction would occur,
for example, if the snapshot had no clones and the user-initiated reference count were
zero.
If a snapshot does not qualify for immediate destruction, it is marked for deferred
destruction. In this state, it exists as a usable, visible snapshot until both of the
preconditions listed above are met, at which point it is destroyed.
An inclusive range of snapshots may be specified by separating the first and last
snapshots with a percent sign. The first and/or last snapshots may be left blank, in
which case the filesystem's oldest or newest snapshot will be implied.
Multiple snapshots (or ranges of snapshots) of the same filesystem or volume may be
specified in a comma-separated list of snapshots. Only the snapshot's short name (the
part after the @) should be specified when using a range or comma-separated list to
identify multiple snapshots.
-d
Defer snapshot deletion.
-r
Destroy (or mark for deferred destruction) all snapshots with this name in
descendent file systems.
-R
Recursively destroy all clones of these snapshots, including the clones,
snapshots, and children. If this flag is specified, the -d flag will have no
effect.
-n
Do a dry-run ("No-op") deletion. No data will be deleted. This is useful in
conjunction with the -v or -p flags to determine what data would be deleted.
-p
Print machine-parsable verbose information about the deleted data.
-v
Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R options, as they
can destroy large portions of a pool and cause unexpected behavior for mounted file
systems in use.
zfs destroy filesystem|volume#bookmark
The given bookmark is destroyed.
zfs snapshot [-r] [-o property=value] ... filesystem@snapname|volume@snapname ...
Creates snapshots with the given names. All previous modifications by successful
system calls to the file system are part of the snapshots. Snapshots are taken
atomically, so that all snapshots correspond to the same moment in time. See the
"Snapshots" section for details.
-r
Recursively create snapshots of all descendent datasets.
-o property=value
Sets the specified property; see zfs create for details.
zfs rollback [-rRf] snapshot
Roll back the given dataset to a previous snapshot. When a dataset is rolled back, all
data that has changed since the snapshot is discarded, and the dataset reverts to the
state at the time of the snapshot. By default, the command refuses to roll back to a
snapshot other than the most recent one. In order to do so, all intermediate snapshots
and bookmarks must be destroyed by specifying the -r option.
The -rR options do not recursively destroy the child snapshots of a recursive
snapshot. Only direct snapshots of the specified filesystem are destroyed by either of
these options. To completely roll back a recursive snapshot, you must rollback the
individual child snapshots.
-r
Destroy any snapshots and bookmarks more recent than the one specified.
-R
Recursively destroy any more recent snapshots and bookmarks, as well as any clones
of those snapshots.
-f
Used with the -R option to force an unmount of any clone file systems that are to
be destroyed.
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
Creates a clone of the given snapshot. See the "Clones" section for details. The
target dataset can be located anywhere in the ZFS hierarchy, and is created as the
same type as the original.
-p
Creates all the non-existing parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent. If the target filesystem or volume already exists, the operation completes
successfully.
-o property=value
Sets the specified property; see zfs create for details.
zfs promote clone-filesystem
Promotes a clone file system to no longer be dependent on its "origin" snapshot. This
makes it possible to destroy the file system that the clone was created from. The
clone parent-child dependency relationship is reversed, so that the origin file system
becomes a clone of the specified file system.
The snapshot that was cloned, and any snapshots previous to this snapshot, are now
owned by the promoted clone. The space they use moves from the origin file system to
the promoted clone, so enough space must be available to accommodate these snapshots.
No new space is consumed by this operation, but the space accounting is adjusted. The
promoted clone must not have any conflicting snapshot names of its own. The rename
subcommand can be used to rename any conflicting snapshots.
zfs rename [-f] filesystem|volume|snapshot
filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
Renames the given dataset. The new target can be located anywhere in the ZFS
hierarchy, with the exception of snapshots. Snapshots can only be renamed within the
parent file system or volume. When renaming a snapshot, the parent file system of the
snapshot does not need to be specified as part of the second argument. Renamed file
systems can inherit new mount points, in which case they are unmounted and remounted
at the new mount point.
-p
Creates all the nonexistent parent datasets. Datasets created in this manner are
automatically mounted according to the mountpoint property inherited from their
parent.
-f
Force unmount any filesystems that need to be unmounted in the process.
zfs rename -r snapshot snapshot
Recursively rename the snapshots of all descendent datasets. Snapshots are the only
dataset that can be renamed recursively.
zfs list [-r|-d depth] [-Hp] [-o property[,...]] [ -t type[,...]] [ -s property ] ... [ -S
property ] ... [filesystem|volume|snapshot] ...
Lists the property information for the given datasets in tabular form. If specified,
you can list property information by the absolute pathname or the relative pathname.
By default, all file systems and volumes are displayed. Snapshots are displayed if the
listsnaps property is on (the default is off). When listing hundreds or thousands of
snapshots performance can be improved by restricting the output to only the name. In
that case, it is recommended to use -o name -s name. The following fields are
displayed by default, name,used,available,referenced,mountpoint.
-H
Used for scripting mode. Do not print headers and separate fields by a single tab
instead of arbitrary white space.
-p
Display numbers in parsable (exact) values.
-r
Recursively display any children of the dataset on the command line.
-d depth
Recursively display any children of the dataset, limiting the recursion to depth.
A depth of 1 will display only the dataset and its direct children.
-o property
A comma-separated list of properties to display. The property must be:
o One of the properties described in the "Native Properties" section
o A user property
o The value name to display the dataset name
o The value space to display space usage properties on file systems and
volumes. This is a shortcut for specifying -o
name,avail,used,usedsnap,usedds,usedrefreserv,usedchild -t
filesystem,volume syntax.
-s property
A property for sorting the output by column in ascending order based on the value
of the property. The property must be one of the properties described in the
"Properties" section, or the special value name to sort by the dataset name.
Multiple properties can be specified at one time using multiple -s property
options. Multiple -s options are evaluated from left to right in decreasing order
of importance.
The following is a list of sorting criteria:
o Numeric types sort in numeric order.
o String types sort in alphabetical order.
o Types inappropriate for a row sort that row to the literal bottom,
regardless of the specified ordering.
o If no sorting options are specified the existing behavior of zfs list
is preserved.
-S property
Same as the -s option, but sorts by property in descending order.
-t type
A comma-separated list of types to display, where type is one of filesystem,
snapshot, snap, volume, bookmark, or all. For example, specifying -t snapshot
displays only snapshots.
zfs set property=value filesystem|volume|snapshot ...
Sets the property to the given value for each dataset. Only some properties can be
edited. See the "Properties" section for more information on what properties can be
set and acceptable values. Numeric values can be specified as exact values, or in a
human-readable form with a suffix of B, K, M, G, T, P, E, Z (for bytes, kilobytes,
megabytes, gigabytes, terabytes, petabytes, exabytes, or zettabytes, respectively).
User properties can be set on snapshots. For more information, see the "User
Properties" section.
zfs get [-r|-d depth] [-Hp] [-o field[,...] [-t type[,...]] [-s source[,...] "all" |
property[,...] filesystem|volume|snapshot ...
Displays properties for the given datasets. If no datasets are specified, then the
command displays properties for all datasets on the system. For each property, the
following columns are displayed:
name Dataset name
property Property name
value Property value
source Property source. Can either be local, default,
temporary, inherited, received, or none (-).
All columns are displayed by default, though this can be controlled by using the -o
option. This command takes a comma-separated list of properties as described in the
"Native Properties" and "User Properties" sections.
The special value all can be used to display all properties that apply to the given
dataset's type (filesystem, volume snapshot, or bookmark).
-r
Recursively display properties for any children.
-d depth
Recursively display any children of the dataset, limiting the recursion to depth.
A depth of 1 will display only the dataset and its direct children.
-H
Display output in a form more easily parsed by scripts. Any headers are omitted,
and fields are explicitly separated by a single tab instead of an arbitrary amount
of space.
-o field
A comma-separated list of columns to display. name,property,value,source is the
default value.
-s source
A comma-separated list of sources to display. Those properties coming from a
source other than those in this list are ignored. Each source must be one of the
following: local,default,inherited,received,temporary,none. The default value is
all sources.
-p
Display numbers in parsable (exact) values.
zfs inherit [-rS] property filesystem|volume|snapshot ...
Clears the specified property, causing it to be inherited from an ancestor, restored
to default if no ancestor has the property set, or with the -S option reverted to the
received value if one exists. See the "Properties" section for a listing of default
values, and details on which properties can be inherited.
-r
Recursively inherit the given property for all children.
-S
Revert the property to the received value if one exists; otherwise operate as if
the -S option was not specified.
zfs upgrade [-v]
Displays a list of file systems that are not the most recent version.
zfs upgrade [-r] [-V version] [-a | filesystem]
Upgrades file systems to a new on-disk version. Once this is done, the file systems
will no longer be accessible on systems running older versions of the software. zfs
send streams generated from new snapshots of these file systems cannot be accessed on
systems running older versions of the software.
In general, the file system version is independent of the pool version. See zpool(8)
for information on the zpool upgrade command.
In some cases, the file system version and the pool version are interrelated and the
pool version must be upgraded before the file system version can be upgraded.
-a
Upgrade all file systems on all imported pools.
filesystem
Upgrade the specified file system.
-r
Upgrade the specified file system and all descendent file systems
-V version
Upgrade to the specified version. If the -V flag is not specified, this command
upgrades to the most recent version. This option can only be used to increase the
version number, and only up to the most recent version supported by this software.
zfs userspace [-Hinp] [-o field[,...]] [-s field] ... [-S field] ... [-t type[,...]]
filesystem|snapshot
Displays space consumed by, and quotas on, each user in the specified filesystem or
snapshot. This corresponds to the userused@user and userquota@user properties.
-n
Print numeric ID instead of user/group name.
-H
Do not print headers, use tab-delimited output.
-p
Use exact (parsable) numeric output.
-o field[,...]
Display only the specified fields from the following set: type, name, used, quota.
The default is to display all fields.
-s field
Sort output by this field. The s and S flags may be specified multiple times to
sort first by one field, then by another. The default is -s type -s name.
-S field
Sort by this field in reverse order. See -s.
-t type[,...]
Print only the specified types from the following set: all, posixuser, smbuser,
posixgroup, smbgroup. The default is -t posixuser,smbuser. The default can be
changed to include group types.
-i
Translate SID to POSIX ID. The POSIX ID may be ephemeral if no mapping exists.
Normal POSIX interfaces (for example, stat(2), ls -l) perform this translation, so
the -i option allows the output from zfs userspace to be compared directly with
those utilities. However, -i may lead to confusion if some files were created by
an SMB user before a SMB-to-POSIX name mapping was established. In such a case,
some files will be owned by the SMB entity and some by the POSIX entity. However,
the -i option will report that the POSIX entity has the total usage and quota for
both.
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ... [-S field] ... [-t type[,...]]
filesystem|snapshot
Displays space consumed by, and quotas on, each group in the specified filesystem or
snapshot. This subcommand is identical to zfs userspace, except that the default types
to display are -t posixgroup,smbgroup.
zfs mount
Displays all ZFS file systems currently mounted.
zfs mount [-vO] [-o options] -a | filesystem
Mounts ZFS file systems. Invoked automatically as part of the boot process.
-o options
An optional, comma-separated list of mount options to use temporarily for the
duration of the mount. See the "Temporary Mount Point Properties" section for
details.
-O
Perform an overlay mount. See mount(8) for more information.
-v
Report mount progress.
-a
Mount all available ZFS file systems. Invoked automatically as part of the boot
process.
filesystem
Mount the specified filesystem.
zfs unmount [-f] -a | filesystem|mountpoint
Unmounts currently mounted ZFS file systems. Invoked automatically as part of the
shutdown process.
-f
Forcefully unmount the file system, even if it is currently in use.
-a
Unmount all available ZFS file systems. Invoked automatically as part of the boot
process.
filesystem|mountpoint
Unmount the specified filesystem. The command can also be given a path to a ZFS
file system mount point on the system.
zfs share -a | filesystem
Shares available ZFS file systems.
-a
Share all available ZFS file systems. Invoked automatically as part of the boot
process.
filesystem
Share the specified filesystem according to the sharenfs and sharesmb properties.
File systems are shared when the sharenfs or sharesmb property is set.
zfs unshare -a | filesystem|mountpoint
Unshares currently shared ZFS file systems. This is invoked automatically as part of
the shutdown process.
-a
Unshare all available ZFS file systems. Invoked automatically as part of the boot
process.
filesystem|mountpoint
Unshare the specified filesystem. The command can also be given a path to a ZFS
file system shared on the system.
zfs bookmark snapshot bookmark
Creates a bookmark of the given snapshot. Bookmarks mark the point in time when the
snapshot was created, and can be used as the incremental source for a zfs send
command.
This feature must be enabled to be used. See zpool-features(5) for details on ZFS
feature flags and the bookmarks feature.
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
Creates a stream representation of the second snapshot, which is written to standard
output. The output can be redirected to a file or to a different system (for example,
using ssh(1). By default, a full stream is generated.
-i snapshot
Generate an incremental stream from the first snapshot (the incremental source) to
the second snapshot (the incremental target). The incremental source can be
specified as the last component of the snapshot name (the @ character and
following) and it is assumed to be from the same file system as the incremental
target.
If the destination is a clone, the source may be the origin snapshot, which must
be fully specified (for example, pool/fs@origin, not just @origin).
-I snapshot
Generate a stream package that sends all intermediary snapshots from the first
snapshot to the second snapshot. For example, -I @a fs@d is similar to -i @a fs@b;
-i @b fs@c; -i @c fs@d. The incremental source may be specified as with the -i
option.
-R
Generate a replication stream package, which will replicate the specified
filesystem, and all descendent file systems, up to the named snapshot. When
received, all properties, snapshots, descendent file systems, and clones are
preserved.
If the -i or -I flags are used in conjunction with the -R flag, an incremental
replication stream is generated. The current values of properties, and current
snapshot and file system names are set when the stream is received. If the -F flag
is specified when this stream is received, snapshots and file systems that do not
exist on the sending side are destroyed.
-D
Generate a deduplicated stream. Blocks which would have been sent multiple times
in the send stream will only be sent once. The receiving system must also support
this feature to receive a deduplicated stream. This flag can be used regardless
of the dataset's dedup property, but performance will be much better if the
filesystem uses a dedup-capable checksum (eg. sha256).
-L
Generate a stream which may contain blocks larger than 128KB. This flag has no
effect if the large_blocks pool feature is disabled, or if the recordsize property
of this filesystem has never been set above 128KB. The receiving system must have
the large_blocks pool feature enabled as well. See zpool-features(5) for details
on ZFS feature flags and the large_blocks feature.
-e
Generate a more compact stream by using WRITE_EMBEDDED records for blocks which
are stored more compactly on disk by the embedded_data pool feature. This flag
has no effect if the embedded_data feature is disabled. The receiving system must
have the embedded_data feature enabled. If the lz4_compress feature is active on
the sending system, then the receiving system must have that feature enabled as
well. See zpool-features(5) for details on ZFS feature flags and the embedded_data
feature.
-p
Include the dataset's properties in the stream. This flag is implicit when -R is
specified. The receiving system must also support this feature.
-n
Do a dry-run ("No-op") send. Do not generate any actual send data. This is
useful in conjunction with the -v or -P flags to determine what data will be sent.
In this case, the verbose output will be written to standard output (contrast with
a non-dry-run, where the stream is written to standard output and the verbose
output goes to standard error).
-P
Print machine-parsable verbose information about the stream package generated.
-v
Print verbose information about the stream package generated. This information
includes a per-second report of how much data has been sent.
The format of the stream is committed. You will be able to receive your streams on
future versions of ZFS.
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
Generate a send stream, which may be of a filesystem, and may be incremental from a
bookmark. If the destination is a filesystem or volume, the pool must be read-only,
or the filesystem must not be mounted. When the stream generated from a filesystem or
volume is received, the default snapshot name will be "--head--".
-i snapshot|bookmark
Generate an incremental send stream. The incremental source must be an earlier
snapshot in the destination's history. It will commonly be an earlier snapshot in
the destination's filesystem, in which case it can be specified as the last
component of the name (the # or @ character and following).
If the incremental target is a clone, the incremental source can be the origin
snapshot, or an earlier snapshot in the origin's filesystem, or the origin's
origin, etc.
-L
Generate a stream which may contain blocks larger than 128KB. This flag has no
effect if the large_blocks pool feature is disabled, or if the recordsize property
of this filesystem has never been set above 128KB. The receiving system must have
the large_blocks pool feature enabled as well. See zpool-features(5) for details
on ZFS feature flags and the large_blocks feature.
-e
Generate a more compact stream by using WRITE_EMBEDDED records for blocks which
are stored more compactly on disk by the embedded_data pool feature. This flag
has no effect if the embedded_data feature is disabled. The receiving system must
have the embedded_data feature enabled. If the lz4_compress feature is active on
the sending system, then the receiving system must have that feature enabled as
well. See zpool-features(5) for details on ZFS feature flags and the embedded_data
feature.
zfs receive [-vnFu] filesystem|volume|snapshot
zfs receive [-vnFu] [-d|-e] filesystem
Creates a snapshot whose contents are as specified in the stream provided on standard
input. If a full stream is received, then a new file system is created as well.
Streams are created using the zfs send subcommand, which by default creates a full
stream. zfs recv can be used as an alias for zfs receive.
If an incremental stream is received, then the destination file system must already
exist, and its most recent snapshot must match the incremental stream's source. For
zvols, the destination device link is destroyed and recreated, which means the zvol
cannot be accessed during the receive operation.
When a snapshot replication package stream that is generated by using the zfs send -R
command is received, any snapshots that do not exist on the sending location are
destroyed by using the zfs destroy -d command.
The name of the snapshot (and file system, if a full stream is received) that this
subcommand creates depends on the argument type and the use of the -d or -e options.
If the argument is a snapshot name, the specified snapshot is created. If the argument
is a file system or volume name, a snapshot with the same name as the sent snapshot is
created within the specified filesystem or volume. If neither of the -d or -e options
are specified, the provided target snapshot name is used exactly as provided.
The -d and -e options cause the file system name of the target snapshot to be
determined by appending a portion of the sent snapshot's name to the specified target
filesystem. If the -d option is specified, all but the first element of the sent
snapshot's file system path (usually the pool name) is used and any required
intermediate file systems within the specified one are created. If the -e option is
specified, then only the last element of the sent snapshot's file system name (i.e.
the name of the source file system itself) is used as the target file system name.
-d
Discard the first element of the sent snapshot's file system name, using the
remaining elements to determine the name of the target file system for the new
snapshot as described in the paragraph above.
-e
Discard all but the last element of the sent snapshot's file system name, using
that element to determine the name of the target file system for the new snapshot
as described in the paragraph above.
-u
File system that is associated with the received stream is not mounted.
-v
Print verbose information about the stream and the time required to perform the
receive operation.
-n
Do not actually receive the stream. This can be useful in conjunction with the -v
option to verify the name the receive operation would use.
-F
Force a rollback of the file system to the most recent snapshot before performing
the receive operation. If receiving an incremental replication stream (for
example, one generated by zfs send -R -[iI]), destroy snapshots and file systems
that do not exist on the sending side.
zfs allow filesystem | volume
Displays permissions that have been delegated on the specified filesystem or volume.
See the other forms of zfs allow for more information.
zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...] filesystem| volume
zfs allow [-ld] -e perm|@setname[,...] filesystem | volume
Delegates ZFS administration permission for the file systems to non-privileged users.
[-ug] "everyone"|user|group[,...]
Specifies to whom the permissions are delegated. Multiple entities can be
specified as a comma-separated list. If neither of the -ug options are specified,
then the argument is interpreted preferentially as the keyword "everyone", then as
a user name, and lastly as a group name. To specify a user or group named
"everyone", use the -u or -g options. To specify a group with the same name as a
user, use the -g options.
[-e] perm|@setname[,...]
Specifies that the permissions be delegated to "everyone." Multiple permissions
may be specified as a comma-separated list. Permission names are the same as ZFS
subcommand and property names. See the property list below. Property set names,
which begin with an at sign (@) , may be specified. See the -s form below for
details.
[-ld] filesystem|volume
Specifies where the permissions are delegated. If neither of the -ld options are
specified, or both are, then the permissions are allowed for the file system or
volume, and all of its descendents. If only the -l option is used, then is allowed
"locally" only for the specified file system. If only the -d option is used, then
is allowed only for the descendent file systems.
Permissions are generally the ability to use a ZFS subcommand or change a ZFS property.
The following permissions are available:
NAME TYPE NOTES
allow subcommand Must also have the permission that is being
allowed
clone subcommand Must also have the 'create' ability and 'mount'
ability in the origin file system
create subcommand Must also have the 'mount' ability
destroy subcommand Must also have the 'mount' ability
diff subcommand Allows lookup of paths within a dataset
given an object number, and the ability to
create snapshots necessary to 'zfs diff'.
mount subcommand Allows mount/umount of ZFS datasets
promote subcommand Must also have the 'mount'
and 'promote' ability in the origin file system
receive subcommand Must also have the 'mount' and 'create' ability
rename subcommand Must also have the 'mount' and 'create'
ability in the new parent
rollback subcommand Must also have the 'mount' ability
send subcommand
share subcommand Allows sharing file systems over NFS or SMB
protocols
snapshot subcommand Must also have the 'mount' ability
groupquota other Allows accessing any groupquota@... property
groupused other Allows reading any groupused@... property
userprop other Allows changing any user property
userquota other Allows accessing any userquota@... property
userused other Allows reading any userused@... property
acltype property
aclinherit property
atime property
canmount property
casesensitivity property
checksum property
compression property
copies property
dedup property
devices property
exec property
filesystem_limit property
logbias property
mlslabel property
mountpoint property
nbmand property
normalization property
primarycache property
quota property
readonly property
recordsize property
refquota property
refreservation property
reservation property
secondarycache property
setuid property
shareiscsi property
sharenfs property
sharesmb property
snapdir property
snapshot_limit property
utf8only property
version property
volblocksize property
volsize property
vscan property
xattr property
zoned property
zfs allow -c perm|@setname[,...] filesystem|volume
Sets "create time" permissions. These permissions are granted (locally) to the creator
of any newly-created descendent file system.
zfs allow -s @setname perm|@setname[,...] filesystem|volume
Defines or adds permissions to a permission set. The set can be used by other zfs
allow commands for the specified file system and its descendents. Sets are evaluated
dynamically, so changes to a set are immediately reflected. Permission sets follow the
same naming restrictions as ZFS file systems, but the name must begin with an "at
sign" (@), and can be no more than 64 characters long.
zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[, ...]] filesystem|volume
zfs unallow [-rld] -e [perm|@setname [,...]] filesystem|volume
zfs unallow [-r] -c [perm|@setname[,...]]
filesystem|volume
Removes permissions that were granted with the zfs allow command. No permissions are
explicitly denied, so other permissions granted are still in effect. For example, if
the permission is granted by an ancestor. If no permissions are specified, then all
permissions for the specified user, group, or everyone are removed. Specifying
"everyone" (or using the -e option) only removes the permissions that were granted to
"everyone", not all permissions for every user and group. See the zfs allow command
for a description of the -ldugec options.
-r
Recursively remove the permissions from this file system and all descendents.
zfs unallow [-r] -s @setname [perm|@setname[,...]]
filesystem|volume
Removes permissions from a permission set. If no permissions are specified, then all
permissions are removed, thus removing the set entirely.
zfs hold [-r] tag snapshot...
Adds a single reference, named with the tag argument, to the specified snapshot or
snapshots. Each snapshot has its own tag namespace, and tags must be unique within
that space.
If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs
destroy command return EBUSY.
-r
Specifies that a hold with the given tag is applied recursively to the snapshots
of all descendent file systems.
zfs holds [-r] snapshot...
Lists all existing user references for the given snapshot or snapshots.
-r
Lists the holds that are set on the named descendent snapshots, in addition to
listing the holds on the named snapshot.
zfs release [-r] tag snapshot...
Removes a single reference, named with the tag argument, from the specified snapshot
or snapshots. The tag must already exist for each snapshot.
If a hold exists on a snapshot, attempts to destroy that snapshot by using the zfs
destroy command return EBUSY.
-r
Recursively releases a hold with the given tag on the snapshots of all descendent
file systems.
zfs diff [-FHt] snapshot snapshot|filesystem
Display the difference between a snapshot of a given filesystem and another snapshot
of that filesystem from a later time or the current contents of the filesystem. The
first column is a character indicating the type of change, the other columns indicate
pathname, new pathname (in case of rename), change in link count, and optionally file
type and/or change time.
The types of change are:
- The path has been removed
+ The path has been created
M The path has been modified
R The path has been renamed
-F
Display an indication of the type of file, in a manner similar to the -F option of
ls(1).
B Block device
C Character device
/ Directory
> Door
| Named pipe
@ Symbolic link
P Event port
= Socket
F Regular file
-H
Give more parsable tab-separated output, without header lines and without arrows.
-t
Display the path's inode change time as the first column of output.
EXAMPLES
Example 1 Creating a ZFS File System Hierarchy
The following commands create a file system named pool/home and a file system named
pool/home/bob. The mount point /export/home is set for the parent file system, and is
automatically inherited by the child file system.
# zfs create pool/home
# zfs set mountpoint=/export/home pool/home
# zfs create pool/home/bob
Example 2 Creating a ZFS Snapshot
The following command creates a snapshot named yesterday. This snapshot is mounted on
demand in the .zfs/snapshot directory at the root of the pool/home/bob file system.
# zfs snapshot pool/home/bob@yesterday
Example 3 Creating and Destroying Multiple Snapshots
The following command creates snapshots named yesterday of pool/home and all of its
descendent file systems. Each snapshot is mounted on demand in the .zfs/snapshot directory
at the root of its file system. The second command destroys the newly created snapshots.
# zfs snapshot -r pool/home@yesterday
# zfs destroy -r pool/home@yesterday
Example 4 Disabling and Enabling File System Compression
The following command disables the compression property for all file systems under
pool/home. The next command explicitly enables compression for pool/home/anne.
# zfs set compression=off pool/home
# zfs set compression=on pool/home/anne
Example 5 Listing ZFS Datasets
The following command lists all active file systems and volumes in the system. Snapshots
are displayed if the listsnaps property is on. The default is off. See zpool(8) for more
information on pool properties.
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
pool 450K 457G 18K /pool
pool/home 315K 457G 21K /export/home
pool/home/anne 18K 457G 18K /export/home/anne
pool/home/bob 276K 457G 276K /export/home/bob
Example 6 Setting a Quota on a ZFS File System
The following command sets a quota of 50 Gbytes for pool/home/bob.
# zfs set quota=50G pool/home/bob
Example 7 Listing ZFS Properties
The following command lists all properties for pool/home/bob.
# zfs get all pool/home/bob
NAME PROPERTY VALUE SOURCE
pool/home/bob type filesystem -
pool/home/bob creation Tue Jul 21 15:53 2009 -
pool/home/bob used 21K -
pool/home/bob available 20.0G -
pool/home/bob referenced 21K -
pool/home/bob compressratio 1.00x -
pool/home/bob mounted yes -
pool/home/bob quota 20G local
pool/home/bob reservation none default
pool/home/bob recordsize 128K default
pool/home/bob mountpoint /pool/home/bob default
pool/home/bob sharenfs off default
pool/home/bob checksum on default
pool/home/bob compression on local
pool/home/bob atime on default
pool/home/bob devices on default
pool/home/bob exec on default
pool/home/bob setuid on default
pool/home/bob readonly off default
pool/home/bob zoned off default
pool/home/bob snapdir hidden default
pool/home/bob acltype off default
pool/home/bob aclinherit restricted default
pool/home/bob canmount on default
pool/home/bob shareiscsi off default
pool/home/bob xattr on default
pool/home/bob copies 1 default
pool/home/bob version 4 -
pool/home/bob utf8only off -
pool/home/bob normalization none -
pool/home/bob casesensitivity sensitive -
pool/home/bob vscan off default
pool/home/bob nbmand off default
pool/home/bob sharesmb off default
pool/home/bob refquota none default
pool/home/bob refreservation none default
pool/home/bob primarycache all default
pool/home/bob secondarycache all default
pool/home/bob usedbysnapshots 0 -
pool/home/bob usedbydataset 21K -
pool/home/bob usedbychildren 0 -
pool/home/bob usedbyrefreservation 0 -
pool/home/bob logbias latency default
pool/home/bob dedup off default
pool/home/bob mlslabel none default
pool/home/bob relatime off default
The following command gets a single property value.
# zfs get -H -o value compression pool/home/bob
on
The following command lists all properties with local settings for pool/home/bob.
# zfs get -r -s local -o name,property,value all pool/home/bob
NAME PROPERTY VALUE
pool/home/bob quota 20G
pool/home/bob compression on
Example 8 Rolling Back a ZFS File System
The following command reverts the contents of pool/home/anne to the snapshot named
yesterday, deleting all intermediate snapshots.
# zfs rollback -r pool/home/anne@yesterday
Example 9 Creating a ZFS Clone
The following command creates a writable file system whose initial contents are the same
as pool/home/bob@yesterday.
# zfs clone pool/home/bob@yesterday pool/clone
Example 10 Promoting a ZFS Clone
The following commands illustrate how to test out changes to a file system, and then
replace the original file system with the changed one, using clones, clone promotion, and
renaming:
# zfs create pool/project/production
populate /pool/project/production with data
# zfs snapshot pool/project/production@today
# zfs clone pool/project/production@today pool/project/beta
make changes to /pool/project/beta and test them
# zfs promote pool/project/beta
# zfs rename pool/project/production pool/project/legacy
# zfs rename pool/project/beta pool/project/production
once the legacy version is no longer needed, it can be destroyed
# zfs destroy pool/project/legacy
Example 11 Inheriting ZFS Properties
The following command causes pool/home/bob and pool/home/anne to inherit the checksum
property from their parent.
# zfs inherit checksum pool/home/bob pool/home/anne
The following command causes pool/home/bob to revert to the received value for the quota
property if it exists.
# zfs inherit -S quota pool/home/bob
Example 12 Remotely Replicating ZFS Data
The following commands send a full stream and then an incremental stream to a remote
machine, restoring them into poolB/received/fs@aand poolB/received/fs@b, respectively.
poolB must contain the file system poolB/received, and must not initially contain
poolB/received/fs.
# zfs send pool/fs@a | \
ssh host zfs receive poolB/received/fs@a
# zfs send -i a pool/fs@b | ssh host \
zfs receive poolB/received/fs
Example 13 Using the zfs receive -d Option
The following command sends a full stream of poolA/fsA/fsB@snap to a remote machine,
receiving it into poolB/received/fsA/fsB@snap. The fsA/fsB@snap portion of the received
snapshot's name is determined from the name of the sent snapshot. poolB must contain the
file system poolB/received. If poolB/received/fsA does not exist, it is created as an
empty file system.
# zfs send poolA/fsA/fsB@snap | \
ssh host zfs receive -d poolB/received
Example 14 Setting User Properties
The following example sets the user-defined com.example:department property for a dataset.
# zfs set com.example:department=12345 tank/accounting
Example 15 Creating a ZFS Volume as an iSCSI Target Device
The following example shows how to create a ZFS volume as an iSCSI target.
# zfs create -V 2g pool/volumes/vol1
# zfs set shareiscsi=on pool/volumes/vol1
# iscsitadm list target
Target: pool/volumes/vol1
iSCSI Name:
iqn.1986-03.com.sun:02:7b4b02a6-3277-eb1b-e686-a24762c52a8c
Connections: 0
After the iSCSI target is created, set up the iSCSI initiator. For more information about
the Solaris iSCSI initiator, see iscsitadm(1M).
Example 16 Performing a Rolling Snapshot
The following example shows how to maintain a history of snapshots with a consistent
naming scheme. To keep a week's worth of snapshots, the user destroys the oldest snapshot,
renames the remaining snapshots, and then creates a new snapshot, as follows:
# zfs destroy -r pool/users@7daysago
# zfs rename -r pool/users@6daysago @7daysago
# zfs rename -r pool/users@5daysago @6daysago
# zfs rename -r pool/users@4daysago @5daysago
# zfs rename -r pool/users@3daysago @4daysago
# zfs rename -r pool/users@2daysago @3daysago
# zfs rename -r pool/users@yesterday @2daysago
# zfs rename -r pool/users@today @yesterday
# zfs snapshot -r pool/users@today
Example 17 Setting sharenfs Property Options on a ZFS File System
The following commands show how to set sharenfs property options to enable rw access for a
set of IP addresses and to enable root access for system neo on the tank/home file system.
# zfs set sharenfs='rw=@123.123.0.0/16,root=neo' tank/home
If you are using DNS for host name resolution, specify the fully qualified hostname.
Example 18 Delegating ZFS Administration Permissions on a ZFS Dataset
The following example shows how to set permissions so that user cindys can create,
destroy, mount, and take snapshots on tank/cindys. The permissions on tank/cindys are also
displayed.
# zfs allow cindys create,destroy,mount,snapshot tank/cindys
# zfs allow tank/cindys
-------------------------------------------------------------
Local+Descendent permissions on (tank/cindys)
user cindys create,destroy,mount,snapshot
-------------------------------------------------------------
Because the tank/cindys mount point permission is set to 755 by default, user cindys will
be unable to mount file systems under tank/cindys. Set an ACL similar to the following
syntax to provide mount point access:
# chmod A+user:cindys:add_subdirectory:allow /tank/cindys
Example 19 Delegating Create Time Permissions on a ZFS Dataset
The following example shows how to grant anyone in the group staff to create file systems
in tank/users. This syntax also allows staff members to destroy their own file systems,
but not destroy anyone else's file system. The permissions on tank/users are also
displayed.
# zfs allow staff create,mount tank/users
# zfs allow -c destroy tank/users
# zfs allow tank/users
-------------------------------------------------------------
Create time permissions on (tank/users)
create,destroy
Local+Descendent permissions on (tank/users)
group staff create,mount
-------------------------------------------------------------
Example 20 Defining and Granting a Permission Set on a ZFS Dataset
The following example shows how to define and grant a permission set on the tank/users
file system. The permissions on tank/users are also displayed.
# zfs allow -s @pset create,destroy,snapshot,mount tank/users
# zfs allow staff @pset tank/users
# zfs allow tank/users
-------------------------------------------------------------
Permission sets on (tank/users)
@pset create,destroy,mount,snapshot
Create time permissions on (tank/users)
create,destroy
Local+Descendent permissions on (tank/users)
group staff @pset,create,mount
-------------------------------------------------------------
Example 21 Delegating Property Permissions on a ZFS Dataset
The following example shows to grant the ability to set quotas and reservations on the
users/home file system. The permissions on users/home are also displayed.
# zfs allow cindys quota,reservation users/home
# zfs allow users/home
-------------------------------------------------------------
Local+Descendent permissions on (users/home)
user cindys quota,reservation
-------------------------------------------------------------
cindys% zfs set quota=10G users/home/marks
cindys% zfs get quota users/home/marks
NAME PROPERTY VALUE SOURCE
users/home/marks quota 10G local
Example 22 Removing ZFS Delegated Permissions on a ZFS Dataset
The following example shows how to remove the snapshot permission from the staff group on
the tank/users file system. The permissions on tank/users are also displayed.
# zfs unallow staff snapshot tank/users
# zfs allow tank/users
-------------------------------------------------------------
Permission sets on (tank/users)
@pset create,destroy,mount,snapshot
Create time permissions on (tank/users)
create,destroy
Local+Descendent permissions on (tank/users)
group staff @pset,create,mount
-------------------------------------------------------------
Example 23 Showing the differences between a snapshot and a ZFS Dataset
The following example shows how to see what has changed between a prior snapshot of a ZFS
Dataset and its current state. The -F option is used to indicate type information for the
files affected.
# zfs diff -F tank/test@before tank/test
M / /tank/test/
M F /tank/test/linked (+1)
R F /tank/test/oldname -> /tank/test/newname
- F /tank/test/deleted
+ F /tank/test/created
M F /tank/test/modified
Example 24 Creating a bookmark
The following example create a bookmark to a snapshot. This bookmark can then be used
instead of snapshot in send streams.
# zfs bookmark rpool@snapshot rpool#bookmark
ENVIRONMENT VARIABLES
ZFS_ABORT
Cause zfs to dump core on exit for the purposes of running ::findleaks.
EXIT STATUS
The following exit values are returned:
0
Successful completion.
1
An error occurred.
2
Invalid command line options were specified.
SEE ALSO
chmod(2), fsync(2), gzip(1), mount(8), ssh(1), stat(2), write(2), zpool(8)